1. Field of the Invention
The present invention relates to X-ray diagnostic systems, and in particular, to such systems for angiographic examinations employing an image intensifier television chain, an image substraction device with at least one image memory whose image data are subtracted from image data taken at times other than the stored image data, and devices for displaying and recording successive television subtraction images.
2. Description of the Prior Art
An X-ray diagnostic system is described in German patent application No. P 31 22 098.3. That system includes an image memory in which can be stored a single X-ray image, or several integrated X-ray images, obtained prior to subjecting the radiography patient to an injection of an X-ray contrast medium. Such an image is known as a blank image. After injection of the contrast medium, an image known as a filling image is taken of the same region as the blank image. The blank image is subtracted from the filling image, thereby producing a real-time fluoroscope image showing only the blood vessels important to the diagnosis.
Also in that system, a video tape recorder is provided for storing individual images takes so that the image subtraction may later be performed on the basis of a selected stored tape. To do this, however, it is necessary to seek and find specific locations on the tape. This can be inconveniently time consuming. Furthermore, the analog storage of the picture signals on the tape is associated with a loss of image quality.